Lockout-tagout systems and methods

Abstract

A transfer switch including a lockout-tagout assembly and lockout-tagout method are provided. An example method includes a latch of a transfer switch actuating a first switch, wherein actuating the first switch sends an inhibit signal to an electronic controller of the transfer switch. The example method further includes the latch actuating a second switch, wherein actuating the second switch opens operator cutoff thereby preventing function of an operator assembly of the transfer switch. Still further, the example method includes, after the latch actuating the first switch and the second switch, locking the latch so as to mechanically prevent the source contact from closing.

What is claimed is: 
     
       1. A transfer switch comprising:
 a switch-panel assembly comprising:
 a first source contact; 
 a second source contact; and 
 an electronic controller; 
 
 a lockout-tagout assembly comprising:
 a first mechanical latch having a first handle, wherein the first mechanical latch is configured to (i) during rotation of the first handle, (a) actuate a first switch so as to send an inhibit signal to the electronic controller and (b) actuate a second switch so as to disable a first operator thereby preventing closing of the first source contact and (ii) after actuating the first switch and the second switch, (a) move in a proximal direction and (b) lock so as to mechanically prevent the first source contact from closing; and 
 a second mechanical latch having a second handle, wherein the second mechanical latch is configured to (i) during rotation of the second handle, (a) actuate a third switch so as to send an inhibit signal to the electronic controller and (b) actuate a fourth switch so as to disable a second operator thereby preventing closing of the second source contact and (ii) after actuating the third switch and the fourth switch, (a) move in a proximal direction and (b) lock so as to mechanically prevent the second source contact from closing. 
 
 
     
     
       2. The transfer switch of  claim 1 , wherein the first source contact is a contact for contacting a utility power source, and wherein the second source contact is a contact for contacting a generator power source. 
     
     
       3. The transfer switch of  claim 1 , wherein the first mechanical latch comprises a slide having a slide slot, and wherein the transfer switch further comprises:
 a contact shaft, wherein the contact shaft is in communication with the first source contact and the slide; and 
 a latching hub fixed on an end of the contact shaft, wherein the latching hub is arranged in the slide slot. 
 
     
     
       4. The transfer switch of  claim 3 , wherein the slide slot comprises proximal end and a distal end, wherein the proximal end is shaped so as to allow for the latching hub to rotate between a first position in which the first source contact is closed and a second position in which the source contact is open, and wherein the distal end is sized such that interference between the distal end and the latching hub prevents the latching hub from entering the distal end when the latching hub is in the first position. 
     
     
       5. The transfer switch of  claim 4 , wherein rotating between the first position and the second position comprises rotating about 90 degrees. 
     
     
       6. The transfer switch of  claim 3 , wherein the first latch comprises an actuation rod connecting the first handle to the slide. 
     
     
       7. The transfer switch of  claim 6 , wherein the lockout-tagout assembly further comprises a torsion hub rotationally fixed to the actuation rod, wherein the torsion hub is configured to contact the first switch and the second switch in order to actuate the first and second switches as the first handle is rotated. 
     
     
       8. The transfer switch of  claim 7 , wherein the torsion hub comprises a torsion-hub hole having a shape corresponding to the shape of the actuation rod, and wherein the actuation rod can move laterally along an axis through the torsion-hub hole. 
     
     
       9. The transfer switch of  claim 7 , wherein the torsion hub comprises:
 a first cam surface for actuating the first switch; and 
 a second cam surface for actuating the second switch. 
 
     
     
       10. The transfer switch of  claim 7 , wherein the actuating rod comprises a padlock hole that is exposed when the first handle is moved a threshold amount in the proximal direction. 
     
     
       11. The transfer switch of  claim 1 , wherein the lockout-tagout assembly further comprises:
 an automatic return feature comprising at least one spring, wherein the automatic return feature is configured to, in response to the first mechanical latch transitioning from a locked state to an unlocked state, automatically return the first mechanical latch to an initial position in which inhibit switch and operator cutoff switches are deactivated and closing of the first source contact is possible. 
 
     
     
       12. The transfer switch of  claim 1 , wherein the second mechanical latch comprises a slide having a slide slot, and wherein the transfer switch further comprises:
 a contact shaft, wherein the contact shaft is in communication with the second source contact and the slide; and 
 a latching hub fixed on an end of the contact shaft, wherein the latching hub is arranged in the slide slot. 
 
     
     
       13. A method comprising:
 a latch of a transfer switch actuating a first switch, wherein actuating the first switch sends an inhibit signal to an electronic controller of the transfer switch; 
 the latch actuating a second switch, wherein actuating the second switch opens an operator cutoff thereby preventing function of an operator assembly of the transfer switch; and 
 after the latch actuating the first switch and the second switch, locking the latch so as to mechanically prevent the source contact from closing. 
 
     
     
       14. The method of  claim 13 , wherein actuating the first and second switch takes place as a latch handle of the latch is rotated. 
     
     
       15. The method of  claim 14 , wherein locking the latch so as to mechanically prevent the source contact from closing comprises moving the latch handle in a proximal direction. 
     
     
       16. The method of  claim 15 , further comprising:
 before the latch handle is rotated at least a threshold amount, an inner lock of the latch preventing the latch handle from being moved in the proximal direction. 
 
     
     
       17. The method of  claim 15 , wherein locking the latch so as to mechanically prevent the source contact from closing further comprises a padlock preventing the latch from rotating. 
     
     
       18. The method of  claim 13 , further comprising:
 after locking the latch so as to mechanically prevent the source contact from closing, unlocking the latch; and 
 after unlocking the latch, the latch automatically returning to an initial position in which the transfer switch is active and it is possible to close the source contact. 
 
     
     
       19. The method of  claim 13 , wherein the source contact is a contact for contacting a generator power source or a utility power source. 
     
     
       20. A transfer switch comprising:
 a source contact; 
 a first switch in communication with an electronic controller; 
 a second switch in communication with an operator of the transfer switch; 
 a mechanical latch assembly comprising (i) a slide having a slide slot, (ii) a handle, and (iii) an actuation rod connecting the handle to the slide, wherein the actuation rod is rotatable about an axis and moveable along the axis; 
 a contact shaft in communication with the source contact and the slide; 
 a latching hub fixed on an end of the contact shaft, wherein the latching hub is arranged in the slide slot; 
 a torsion hub rotationally fixed to the actuation rod, wherein the torsion hub is configured to actuate the first switch and the second switch as the handle is rotated from a first position to a second position, wherein actuating the first switch sends an inhibit signal to the electronic controller and actuating the second switch disables the operator thereby preventing closing of the source contact, 
 wherein the actuation rod is prevented from moving in a proximal direction along the axis when the handle is in the first position, and wherein the actuation rod is configured to move in the proximal direction along the axis after the handle is rotated from the first position to the second position.